The present invention relates to housewares and, more particularly, to vacuum cleaners.
Vacuum cleaners are almost indispensable houseware appliances for household cleaning. Generally, they consist of a fan or blower operative to produce a partial vacuum at an intake. Air sucked in by the partial vacuum passes through a filter bag, whereby dirt particles are removed from the air stream. The filtered air is returned to the environment.
Pure-vacuum cleaners, such as described above, are most suited to removing dust, dirt and hair from hard surfaces such as, for example, wood or tile. Dust, dirt and hair found on a carpet or fabric may adhere so strongly thereto that a vacuum-only cleaner may be incapable of satisfactory cleaning. Vacuum cleaners meet this additional problem with a rotating cylindrical brush contacting the surface being cleaned. The brush tends to dislodge dust, dirt and hair which is thereupon entrained in the air stream created by the partial vacuum. Once moving in the air stream, the dust, dirt and hair is filtered from the air stream by the filter bag.
Vacuum cleaners are called upon to clean bare surfaces as well as carpeted surfaces. The bristles of a rotary brush having a length appropriate for contacting the surface of a carpet are too short to contact a hard surface. Conversely, bristles that are long enough to contact a hard surface conventionally bear too hard upon a carpet.
The prior art responds to the problem of differing height requirements for hard and carpeted surfaces by providing means for raising and lowering the floor tool of the vacuum cleaner to a selectable height above the surface. Such a provision adds substantially to the cost of the floor tool.